The present invention is directed to a method of and apparatus for forming concrete liner in a vertical shaft; particularly where the diameter of the bore is large. For example, the disclosed embodiment may form a liner for a shaft in a coal mine wherein the inner diameter of the shaft after the lining is installed in twenty-two feet. The method and apparatus have application beyond the field of coal mining, but as indicated above, it has particular application in the formation of liners for shafts of large diameter.
A current technique for lining large diameter bores with concrete requires that forms be set for a curb ring located at a distance beneath a previously formed curb ring. The new curb ring is then formed by pouring concrete into the forms. Next, forms are placed between the two curb rings, spaced inwardly from the wall of the shaft by the desired thickness of the liner section; and that liner section is poured. A new curb ring is formed at a lower depth, again by setting suitable forms in pouring the new curb ring. Finally, the liner forms are disassembled from the most recently poured section and re-assembled at the lower level. The process is continued until the liner is completely formed.